(a) Field of the Invention
The present invention relates to a drive control method for stepping motors.
(b) Description of the Prior Art
Conventionally, for example, in a fuel supply device for internal combustion engines in which the air amount to be supplied to the engine is adapted to be controlled by a throttle actuator comprising a stepping motor, the opening angle .theta. of the throttle valve is stepwisely determined in correspondence to each unit step S of the stepping motor. Referring to FIG. 1, it shall be explained briefly in the following. In case an opening angle .theta..sub.F of the throttle valve to give a desired air amount QA.sub.F is between the opening angle .theta..sub.1 at the first step S.sub.1 of the stepping motor and the opening angle .eta..sub.2 at the second step S.sub.2 to follow the first step S.sub.1, this air amount QA.sub.F is substituted by either one of the air amount QA.sub.1 of the opening angle .theta..sub.1 and the air amount QA.sub.2 by the opening angle .theta..sub.2. Therefore, this kind of the device has such a defect as not able to realize the above mentioned proper opening angle by being regulated by the stepwise action of the stepping motor or by the step even when a proper opening angle is obtained with high accuracy basing upon various driving data. Therefore, such a method as to use a micro step is thought of, but it is not apt for practical uses due to the inaccuracy of the action thereof.